A kind of controllable silicon light modulation circuit, light-dimming method and a kind of led drive circuit of using it
Technical field
The present invention relates to a kind of light adjusting circuit that is applied to drive lamp load, more relate to a kind of controllable silicon light modulation circuit, controllable silicon light modulation method specifically and use its a kind of led drive circuit.
Background technology
For lighting field, because controllable silicon phased (copped wave method) light-dimming method has that volume is little, reasonable price and the wide advantage of light modulation power bracket, therefore controllable silicon phase-controlled dimming method is the light-dimming method that is most widely used at present, is widely used in stage illumination, lighting and ambient lighting field.Using silicon controlled phased operation principle, by the angle of flow of control silicon controlled rectifier, the sine voltage that AC network is imported cuts away a part, to reduce average value of output voltage, thereby the supply power voltage of control circuit for lamp is realized the dimming function to lamp load.
With reference to Figure 1A, be depicted as a kind of light adjusting circuit theory diagram of existing employing controllable silicon phase-controlled dimming method, it comprises the filter circuit that exchanges input source 101, silicon controlled rectifier 106, circuits for triggering 113, rectifier bridge 107, keeps resistance 108 and be made up of diode 109 and filter capacitor 110.Wherein, circuits for triggering 113 can be for forming by bidirectional trigger diode 105, rectifier bridge 107 and by several parts such as adjustable resistance 102, resistance 103 and electric capacity 103.The anode of silicon controlled rectifier 106 receives an end that exchanges input source 101, and negative electrode is connected to rectifier bridge 107; A ' point in the circuits for triggering that the adjustable resistance 102 that is connected in series successively, resistance 103 and electric capacity 103 are formed is connected to the control utmost point of silicon controlled rectifier 106.
In the course of the work, by regulating the resistance value of
adjustable resistance 102, change the voltage of the silicon controlled
rectifier 106 control utmost points, when the voltage of the control utmost point during greater than certain voltage, silicon controlled
rectifier 106 beginning conductings, thus the angle of flow of control silicon controlled
rectifier 106 is with respect to the phase place that exchanges input source 101.The phase-controlled dimming work wave schematic diagram that triggers from the controllable silicon forward position shown in Figure 1B as can be seen, a certain moment t behind the voltage zero-cross of simple alternating current input source 101
1(or a certain phase place w
T1), in the control extremely of silicon controlled
rectifier 106, add a positive triggering pulse V
Trg1, make silicon controlled
rectifier 106 triggering and conducting, according to the switching characteristic of silicon controlled rectifier, this conducting will be maintained to sinusoidal wave positive half cycle and finish.So in the positive half cycle (i.e. 0~π interval) of sine wave, 0~w
T1Be in the α pilot angle in the scope, silicon controlled
rectifier 106 not conductings; And at w
T1Between the phase region of~π be
Controllable silicon conducting in the angle of flow, this scope is seen the oblique line part among Figure 1B).Same negative half period at sinusoidal ac is at t
2(be phase angle w constantly
T2) apply trigger impulse V
Trg2, make its conducting.So go round and begin again, each half period of offset of sinusoidal ripple is controlled its conducting, obtains the identical angle of flow.Triggered time (or phase place) by the change trigger impulse just can change thyristor operating angle
The size of (or pilot angle α), thus the alternating voltage V of a phase shortage obtained
Acin, after
process rectifier bridge 107 carries out rectification, obtain a direct current voltage V
Dcin, the visible angle of flow
Big more, the output voltage V of circuit
DcHigh more, control by power stage circuit and 111 pairs of
loads 112 of drive circuit, thereby make the luminous bright more of
load 112.
Because controllable silicon is in closed condition during by zero crossing, traditional ac/dc switch mode led driver can be closed, load that simultaneously can't driving LED.Therefore, controllable silicon dimmer is under the situation of the extremely low angle of flow, and human eye will pick out LED and load on short opening time under the doubled frequency (as 100Hz/120Hz), the flicker effect that goes out that causes eyes to see.
Therefore, make silicon controlled rectifier TRIAC maintain the minimum requirements of initial state, just must satisfy the electric current of keeping of its requirement.The ac/dc led driver of many employing bridge rectifiers generally all has a filter circuit and carries out filtering with the bigger direct voltage of fluctuation to rectifier bridge output, as bigger filter capacitor 110.Therefore, electric current only occurs in a bit of time when voltage peak occurs, and does not occur and do not have electric current in all the other times of each half period.Therefore there are not enough alternating currents can keep the conducting of TRIAC.
Usually, when externally fed voltage is in the smaller value state, in order to access the electric current of keeping silicon controlled rectifier TRIAC normally, must increase the extra resistance 108 of keeping and keep this normal current, therefore inevitably brought extra power loss, reduced the operating efficiency of circuit, the light modulation service behaviour is poor.
Summary of the invention
In view of this, the object of the present invention is to provide a kind of high efficiency, flicker free, preferable controllable silicon light modulation circuit and the light-dimming method thereof of dimming behavior.
Because the existence of filter capacitor, make electric current between an initial phase angle relevant with the AC supply voltage value and 90 ° of phase angles, exist, so utilize this phase angular region to carry out light modulation and operate with the capacitance of filter capacitor, avoid keeping the use of resistance.
Preferred embodiment according to a kind of controllable silicon light modulation circuit of the present invention comprises,
One SCR rectification circuit, it comprises a silicon controlled rectifier, in order to receiving described AC power, and exports the ac voltage signal of a phase shortage;
One rectifier bridge is connected with the output of described SCR rectification circuit, in order to receiving the ac voltage signal of described phase shortage, and is converted into the d. c. voltage signal of a phase shortage;
The d. c. voltage signal of described phase shortage produces a level and smooth direct voltage by a filter capacitor, provides power supply to give back level driver;
Conducting phase angle signal generation circuit is connected with described rectifier bridge, in order to receiving the d. c. voltage signal of described phase shortage, and produces a control signal that characterizes described silicon controlled rectifier conducting phase angular region;
Dim signal generation circuit, it has one by default initial phase angle with by the definite phase angle dimming scope of phase angle, and described phase angle dimming scope is determined by the numerical value of described filter capacitor and described AC power;
Described dim signal generation circuit is connected with described conducting phase angle signal generation circuit, in order to receiving a described control signal and a reference ramp signal, and both is compared, and the result is as described dim signal in its output;
Described described AC power of reference ramp characterization half period is at the mean value at each phase angle place, have the first reference value corresponding with initial phase angle and with by the second corresponding fiducial value of phase angle;
When described control signal equaled described first reference value, described dim signal was controlled described LED lamp load with high-high brightness work;
When described control signal equaled described second fiducial value, described dim signal was controlled described LED lamp load with minimum brightness work;
When described control signal is between the described first reference value and second fiducial value, described dim signal control LED lamp load continuous linear change between high-high brightness and minimum brightness;
When control signal during less than described second fiducial value, described dim signal is controlled described follow-up LED lamp load with a default constant brightness job.
Preferably, described initial phase angle is the phase angle between 0 °-90 °, and described is 90 ° of phase angles by phase angle.
Further, described conducting phase angle signal generation circuit further comprises:
Phase angle detection circuit is connected with the output of described rectifier bridge, in order to the d. c. voltage signal of the phase shortage that receives the output of described rectifier bridge, to export a square-wave signal;
Control signal generation circuit is connected with described phase angle detection circuit, in order to receiving described square-wave signal, and it is put in order and Filtering Processing, to obtain the control signal of a level and smooth relatively sign silicon controlled rectifier conducting phase angular region.
Further, described phase-angle detection testing circuit further comprises a clamp circuit and a transistor of being made up of voltage stabilizing didoe, and the puncture voltage of described voltage stabilizing didoe is set to and the corresponding ac voltage of described initial phase angle; The anode of described voltage stabilizing didoe is connected to second output of described rectifier bridge, and negative electrode is connected to first output of described rectifier bridge by a resistance; Described transistorized control end is connected to the negative electrode of described voltage stabilizing didoe, and first end is connected to first output of described rectifier bridge; Second end is connected to ground by a resistance, to obtain the square-wave signal of a sign silicon controlled rectifier conducting phase angular region.
Further, described control signal generation circuit further comprises first filter circuit that first inverter and is made up of resistance and electric capacity, one termination of described inverter is received described square-wave signal, and described resistance and electric capacity are connected in series in the other end of described inverter and second output of described rectifier bridge successively; The voltage of the points of common connection of described resistance and electric capacity is as described control signal.
Preferably, described dim signal generation circuit further comprises:
The reference ramp signal generating circuit, in order to produce to characterize the mean value of described AC power of half period at each phase angle place, have the first reference value corresponding with initial phase angle and with by the second corresponding fiducial value of phase angle;
Comparison and treatment circuit, its first input end receives described control signal, and second input receives described reference ramp signal, and both are compared and treated, with the dim signal as described controllable silicon light modulation circuit output, to regulate the brightness of back lamp load.
Preferred embodiment according to a kind of controllable silicon light modulation method of the present invention may further comprise the steps:
Receive outside input ac power, utilize SCR rectification circuit to be converted into the alternating voltage of a phase shortage;
Receive the alternating voltage of described phase shortage, and it is carried out rectification, to obtain the direct voltage of a phase shortage;
Receive the direct voltage of described phase shortage, and it is changed, to obtain the control signal of a sign silicon controlled rectifier conducting phase angular region;
A described control signal and a reference ramp signal are compared, and comparative result is as described dim signal;
When control signal equals the first reference value of described ramp signal, export a dim signal, make that this moment, the LED lamp was in the high-high brightness state;
When control signal equals second fiducial value of described ramp signal, export a dim signal, make that this moment, the LED lamp was in the minimum brightness state;
When control signal is between the first reference value of described ramp signal and second fiducial value, export a dim signal, between LED high-high brightness state and minimum brightness state, to regulate the brightness of LED lamp load continuously;
When control signal during less than second fiducial value, described dim signal is controlled described follow-up LED lamp load with a default constant brightness job.
Further, further comprise:
Receive the direct voltage of described phase shortage, and it is carried out clamp, to obtain the square-wave signal of the described silicon controlled rectifier conducting phase angular region of a sign;
Receive described square-wave signal, and carry out filtering operation, characterize the level and smooth voltage signal of described silicon controlled rectifier conducting phase angular region to obtain one according to a fiducial value.
Preferred embodiment according to a kind of led drive circuit of the present invention comprises described controllable silicon light modulation circuit, also comprises: power stage circuit and drive circuit;
Described power stage circuit and drive circuit receive direct voltage and the described dim signal that described filter capacitor produces, and driving follow-up LED lamp, and carry out the brightness regulation action.
As seen, adopt controllable silicon light modulation circuit of the present invention, its dimming scope is not the whole angle of flow of silicon controlled, promptly finish from trigger angle to a half-sinusoid, but the employing higher segment limit of voltage magnitude wherein, as the scope of initial phase angle to 90 ° phase angle, in this scope, regulate.
Because adjustable range is in the scope of initial phase angle to 90 ° phase angle, therefore voltage magnitude is higher, for the electric current of keeping the silicon controlled rectifier normally, electric current during normally can be kept the silicon controlled operating current, therefore can not need to keep resistance or adopt the bigger resistance of resistance also passable.
Adopt controllable silicon light modulation circuit of the present invention, can not need to keep resistance or adopt the bigger resistance of resistance promptly can satisfy the silicon controlled running current, improved the operating efficiency of circuit, and dimming behavior is good, can have the phenomenon of load lamp flicker.
Description of drawings
Figure 1A is depicted as the theory diagram of a kind of controllable silicon light modulation circuit that adopts prior art;
Figure 1B is depicted as the working waveform figure of the controllable silicon light modulation circuit shown in Figure 1A;
Fig. 2 A is depicted as the schematic block circuit diagram according to an embodiment of controllable silicon light modulation circuit of the present invention;
Fig. 2 B is depicted as the working waveform figure of an embodiment of the controllable silicon light modulation circuit of the present invention of the foundation shown in Fig. 2 A;
Fig. 3 A is depicted as the schematic block circuit diagram according to another embodiment of controllable silicon light modulation circuit of the present invention;
Fig. 3 B is depicted as the working waveform figure of another embodiment of the controllable silicon light modulation circuit of the present invention of the foundation shown in Fig. 3 A;
Figure 4 shows that flow chart according to an embodiment of controllable silicon light modulation method of the present invention.
Embodiment
Below in conjunction with accompanying drawing several preferred embodiments of the present invention is described in detail, but the present invention is not restricted to these embodiment.The present invention contain any on marrow of the present invention and scope, make substitute, modification, equivalent method and scheme.Understand for the public is had completely the present invention, in the following preferred embodiment of the present invention, describe concrete details in detail, and do not have the description of these details also can understand the present invention fully for a person skilled in the art.
Different with the existing controllable silicon light modulation technology shown in Figure 1A, the controllable silicon light modulation circuit according to first embodiment of the invention shown in Fig. 2 A has increased conducting phase angle signal generation circuit 201 and dim signal generation circuit 202.
Conducting phase angle signal generation circuit 201 is connected with the output of described rectifier 107, by the direct voltage V to the phase shortage of rectifier bridge output
DcinDetect, thereby obtain a control signal V who characterizes silicon controlled rectifier 106 angle of flow scopes
Ctrl
Dim signal generation circuit 202 receives the control signal V of described conducting phase angle signal generation circuit 201 outputs
CtrlWith a reference ramp signal V
Ramp, and both being compared, the result is as described dim signal in its output, and produces a dim signal V who characterizes described silicon controlled rectifier conducting phase angular region in view of the above
Ref
Dim signal generation circuit 202, the phase angle dimming scope that it has an initial phase angle of presetting and determines by phase angle, described phase angle dimming scope is determined by the numerical value of described filter capacitor 110 and described AC power 101.
Described reference ramp signal V
RampCharacterize the mean value of described AC power of half period at each phase angle place, have the first reference value corresponding with initial phase angle and with by the second corresponding fiducial value of phase angle;
As described control signal V
CtrlWhen equaling described first reference value, described dim signal V
RefControl described LED lamp load with high-high brightness work;
As described control signal V
CtrlWhen equaling described second fiducial value, described dim signal V
RefControl described LED lamp load with minimum brightness work;
As described control signal V
CtrlIn the time of between the described first reference value and second fiducial value, described dim signal V
RefControl LED lamp load continuous linear change between high-high brightness and minimum brightness;
As control signal V
CtrlDuring less than described second fiducial value, described dim signal V
RefControl described follow-up LED lamp load with default constant brightness (as 10% a brightness) job.
Described initial phase angle is the phase angle between 0 °-90 °, and described is 90 ° of phase angles by phase angle.
Therefore suppose that the phase angular region with respect to the half period sinusoidal voltage that has electric current to flow through described filter capacitor 110 is 30 ° of-90 ° of phase angular regions, then initial phase angle is 30 ° of phase angles, can be with 30 °-90 ° phase angular region as the phase angle dimming scope.In this phase angular region, necessarily there is certain electric current to flow through filter capacitor 110, be enough to provide silicon controlled rectifier 106 to keep the electric current of keeping of normally, thereby in this phase angle dimming scope, regulate the brightness of follow-up lamp load continuously.With reference to figure 2B, be depicted as the reference ramp signal of this moment and the corresponding relation figure between the control signal.The first reference value V of reference ramp signal
Ref1Correspond to the mean value 5V of 30 ° of-180 ° of phase angles
Pi/ 6; The second fiducial value V
Ref2Correspond to the mean value V of 90 ° of-180 ° of phase angles
Pi/ 2.
As described control signal V
CtrlEqual described first reference value V
Ref1The time, described dim signal is controlled described LED lamp load with high-high brightness work;
As described control signal V
CtrlEqual the described second fiducial value V
Ref2The time, described dim signal is controlled described LED lamp load with minimum brightness work;
As described control signal V
CtrlAt described first reference value V
Ref1With the second fiducial value V
Ref2Between the time, described dim signal control LED lamp load linear change continuously between high-high brightness and minimum brightness.
As described control signal V
CtrlGreater than described first reference value V
Ref1The time, described dim signal is controlled described follow-up lamp load 112 with a default constant brightness job (as 10% brightness).
As described control signal V
CtrlLess than the described second fiducial value V
Ref2The time, described dim signal controls that described follow-up lamp load 112 extinguishes or with a default constant brightness job.
As seen, adopt the foundation controllable silicon light modulation circuit of the present invention shown in Fig. 2 A, detect the conducting phase angular region of silicon controlled rectifier 106 by conducting phase angle signal generation circuit 201, and by dim signal generation circuit 202 control its in certain adjusting phase angular region, carry out corresponding light modulation operation.Regulate the phase angular region and determine by filter capacitor and input AC source, thus no longer need resistance less keep resistance 108; And light modulation phase angular region corresponding voltage value is also higher, the problem of the lamp flicker that existing controllable silicon light modulation circuit causes can not occur.
With reference to figure 3A, be depicted as the schematic block circuit diagram of another embodiment of the controllable silicon light modulation circuit of the present invention of the foundation shown in Fig. 2 A.In this embodiment, conducting phase angle signal generation circuit 201 comprises phase angle detection circuit 306 and control signal generation circuit 310; Dim signal generation circuit 202 comprises comparison circuit 316.
Below be that 30 ° of-90 ° of phase angles are example with the phase angle dimming scope, describe the operation principle of this embodiment in detail in conjunction with Fig. 3 B.Fig. 3 B is depicted as the working waveform figure of the described phase angle detection circuit of Fig. 3 A.
Phase angle detection circuit 306 receives the direct voltage V of the phase shortage of rectifier bridge 107 outputs
Dcin, and it is carried out clamp, thereby exports a square-wave signal that characterizes silicon controlled rectifier 106 conducting phase angular regions.
The anode of described voltage stabilizing didoe 301 is connected to second output of described rectifier bridge 107, and negative electrode is connected to first output of described rectifier bridge 107 by a resistance 302, and its points of common connection is the A point; The control end of described transistor 303 is connected to the negative electrode of described voltage stabilizing didoe 301, and first end of described transistor 303 is connected to first output of described rectifier bridge 107, and its second end is connected to ground by a resistance 304, and its points of common connection is the B point.
When the voltage of first output of rectifier bridge 107 during less than the puncture voltage of described voltage stabilizing didoe 301, transistor 303 is in off state, and the voltage that A is ordered is zero; When the voltage of first output of rectifier bridge 107 during greater than the voltage of voltage regulation of described voltage stabilizing didoe 301, transistor 303 conductings, the voltage that A is ordered is the voltage of voltage regulation of described voltage stabilizing didoe 301, thereby obtains the square-wave signal V of a sign silicon controlled rectifier 106 conducting phase angular region ψ at the A point
ASince the pressure drop of transistor 303, the voltage V that B is ordered
BThe voltage of ordering a little less than A.The voltage V that B is ordered
BBe passed to late-class circuit through resistance 305.
Then, by control signal generation circuit 310 this square-wave signal is converted to a level and smooth relatively control signal V
Ctrl
Control signal generation circuit 310 further comprises and is connected in series in voltage source V successively
DDAnd first inverter 307, resistance 308 and electric capacity 309 between second output of rectifier bridge 107, one termination of wherein said first inverter 307 is received described square-wave signal, and described resistance 308 and electric capacity 309 are connected in series in the other end of described inverter 307 and second output of described rectifier bridge 107 successively; The voltage of the points of common connection C of described resistance 308 and electric capacity 309 is as described control signal V
CtrlControl signal V in the output of C end
CtrlNumerical value be:
Wherein, V
PiThe fiducial value of representing first inverter 307, ψ represents the conducting phase angle of silicon controlled rectifier 106.
Preferably, control signal generation circuit 310 can further include transistor 311, transistor 312 and constant-current source 314.Transistor 311 is as voltage V
BDuring greater than the threshold voltage of transistor 311, transistor 311 conductings, electric current, limits by 314 pairs of these electric currents of constant-current source to transistor 312 by transistor 311 mirror images.
Dim signal generation circuit 202 comprises reference ramp signal generating circuit 316 and compares and treatment circuit 315.
Reference ramp signal generating circuit 316 characterizes the reference ramp signal V of described AC power of half period at the mean value at each phase angle place in order to produce
Ramp, have the first reference value V corresponding with initial phase angle
Ref1With with by the second corresponding fiducial value V of phase angle
Ref2
Reference ramp signal generating circuit 316 can adopt various types of ramp signal generation circuit, as counter structure and the constant-current source structures such as charging circuit to electric capacity.
Compare and the described control signal V of treatment circuit 315 receptions
CtrlWith reference ramp signal V
Ramp, so that both are compared in real time, and compared result is carried out respective handling.
As described control signal V
CtrlEqual described first reference value V
Ref1The time, described dim signal is controlled described LED lamp load with high-high brightness work;
As described control signal V
CtrlEqual the described second fiducial value V
Ref2The time, described dim signal is controlled described LED lamp load with minimum brightness work;
As described control signal V
CtrlAt described first reference value V
Rf1With the second fiducial value V
Ref2Between the time, described dim signal control LED lamp load linear change continuously between high-high brightness and minimum brightness.
As described control signal V
CtrlGreater than described first reference value V
Ref1The time, described dim signal is controlled described follow-up lamp load 112 with a default constant brightness job (as 10% brightness).
As described control signal V
CtrlLess than the described second fiducial value V
Ref2The time, described dim signal controls that described follow-up lamp load 112 extinguishes or with a default constant brightness job.
Adopt the controllable silicon light modulation embodiment of circuit shown in Fig. 3 A, conducting phase angular region by conducting phase angle signal generation electric circuit inspection silicon controlled rectifier 106, and by dim signal generation circuit 202 control its in certain adjusting phase angular region, carry out corresponding light modulation operation.
With reference to figure 4, be depicted as flow chart according to a preferred embodiment of controllable silicon light modulation method of the present invention.In this embodiment, may further comprise the steps:
S401: receive outside input ac power, utilize SCR rectification circuit to be converted into the alternating voltage of a phase shortage;
S402: receive the alternating voltage of described phase shortage, and it is carried out rectification, to obtain the direct voltage of a phase shortage;
S403: receive the direct voltage of described phase shortage, and it is changed, to obtain the control signal of a sign silicon controlled rectifier conducting phase angular region;
S404: a described control signal and a reference ramp signal are compared and treated, with as described dim signal.
When control signal equals the first reference value of described ramp signal, export a dim signal, make that this moment, the LED lamp was in the high-high brightness state;
When control signal equals second fiducial value of described ramp signal, export a dim signal, make that this moment, the LED lamp was in the minimum brightness state;
When control signal is between the first reference value of described ramp signal and second fiducial value, export a dim signal, between LED high-high brightness state and minimum brightness state, to regulate the brightness of LED lamp load continuously;
When control signal during greater than described first reference value, described dim signal is controlled described follow-up LED lamp load with a default constant brightness job;
When described control signal during less than described second fiducial value, described dim signal controls that described follow-up LED lamp load extinguishes or with a default constant brightness job.
Preferably, described controllable silicon light modulation method further comprises:
Receive the direct voltage of described phase shortage, and it is carried out clamp, to obtain the square-wave signal of the described silicon controlled rectifier conducting phase angular region of a sign;
Receive described square-wave signal, and carry out filtering operation, characterize the level and smooth voltage signal of described silicon controlled rectifier conducting phase angular region to obtain one according to a fiducial value.
The invention also discloses according to a kind of led drive circuit of the present invention, comprise the controllable silicon light modulation circuit shown in Fig. 2 A or the 3A, also comprise: power stage circuit and drive circuit.
Shown in Fig. 2 A, described power stage circuit and drive circuit 111 receive the direct voltage V that described filter capacitor 110 produces
DcinWith described dim signal V
Ref, driving follow-up LED lamp load 112, and carry out the brightness regulation action.
More than the controllable silicon light modulation circuit and the light-dimming method thereof of foundation the preferred embodiments of the present invention carried out detailed description, those of ordinary skills can know other technologies or structure and circuit layout, element etc. in view of the above by inference and all can be applicable to described embodiment, transistor can be mosfet transistor, and ramp signal generation circuit, filter circuit can be any type of suitable circuit.The control mode that trigger in the forward position of adopting in the embodiments of the invention, those skilled in the art can learn, based on also realizing purpose of the present invention along the control mode that triggers after the employing of inventive concept, reach identical beneficial effect.
As indicated above according to embodiments of the invention, these embodiment do not have all details of detailed descriptionthe, do not limit this invention yet and only are described specific embodiment.Obviously, according to above description, can make many modifications and variations.These embodiment are chosen and specifically described to this specification, is in order to explain principle of the present invention and practical application better, thereby the technical field technical staff can utilize the present invention and the modification on basis of the present invention to use well under making.The present invention only is subjected to the restriction of claims and four corner and equivalent.